/Engine/Source/Runtime/Engine/Public/Animation/AnimInstanceProxy.h
Get Slot Node Weight : this returns new Slot Node Weight, Source Weight, Original TotalNodeWeight this 3 values can't be derived from each other
void GetSlotWeight ( const [FName](API\Runtime\Core\UObject\FName) & SlotNodeName, float & out_SlotNodeWeight, float & out_SourceWeight, float & out_TotalNodeWeight ) const